class Todo(object):
    current_todo_id=0
    @classmethod
    def get_id(cls):
        Todo.current_todo_id+=1
        return Todo.current_todo_id
    def __init__(self,title,id=0,completed=False):
        self.id=id  if id>0 else Todo.get_id()
        self.title=title
        self.completed=completed
    def __str__(self):
        return "id: {}\ntitle: {}\ncompleted: {}".format(self.id,self.title,self.completed)